The present invention is directed generally to the measurement of response time in computer applications and specifically to the use of non-intrusive devices to measure response time in multi-tiered computer networks.
Multi-tiered computer networks are widely used to provide one or more users with a wide variety of information and computer resources. In multi-tiered computer networks, client computers (e.g., users) interact with server computers to perform an application which is partitioned into one or more transactions. An application is a group of meaningful transactions, and a transaction is a unit of meaningful work as perceived by the user. A transaction is typically a collection of service requests, with the service request typically being a collection of service packets. A service packet is simply an item of information, or a message, communicated between computers. In the course of performing a transaction, the client computer may request one or more of the server computers to transfer service packets containing data to the client computer or provide service packets containing data to the server computer(s) to permit the server computer(s) to process the request. The server computers can in turn request the services of other server computers in connection with the data transfer request from the client computer.
Performance monitoring of the network is important to ascertain periods of significant transaction user delays and user productivity. Performance monitoring generally seeks to measure the response time for a transaction or application. The response time is the time required for the servers and network to perform the transaction or application. Statistical analysis can be performed on the response times to facilitate analysis of servers and network performance.
Two methods are commonly used to monitor network performance and provide response times. Intrusive/invasive monitoring techniques alter the software code on the client computer to include a marker command. The marker commands inform a listening device of transmission of the initial service request packet to initiate timing measurement and receipt of the final results or acknowledgement packet to cease timing measurement. Non-intrusive/non-invasive monitoring techniques, in contrast, typically do not alter the software code. Rather, a probe is inserted into a communication line between the client and server computers to monitor the delays between transmission of individual packets between the client and server computers to provide a rough estimate of response time.
Intrusive/invasive and non-intrusive/non-invasive techniques each have a number of drawbacks. In the case of intrusive/invasive techniques, though the transaction response time is provided, few multi-tiered applications are written with embedded marker commands in the code. Even if the applications were to have embedded marker commands, technical problems, can arise due to and consolidation of application-embedded response time statistics to a central location, especially for mobile user computers. In the case of non-intrusive/non-invasive techniques, it is only possible to determine the rate of information transmission between the computers for individual packets. Such techniques are typically unable to determine the response time for a transaction or application. Neither intrusive/invasive nor non-intrusive/non-invasive monitoring techniques are able to match, especially in multi-tiered networks, individual packets with the corresponding transaction to compute a response time for the transaction or related application. As noted above, each of the server computers performing an application can process a series of individual service requests pertaining to a variety of different user transactions. Existing monitoring techniques are unable to match the service packets in the various service requests to a specific transaction.
There is a need for an apparatus and method for measuring the response time for a transaction or an application, especially in multi-tiered computer networks. There is a related need for an apparatus and method for measuring the response time for a transaction or an application using non-intrusive/non-invasive techniques.
There is a need for an apparatus and method for measuring the response time for a transaction or an application that is able to match individual- service packets with the corresponding transaction or application.
The present invention addresses these and other needs by providing in one aspect a method for identifying a transaction corresponding to a plurality of service packets communicated between a source node and a destination node. The method includes the steps: (i) providing a communications data set including a plurality of service packets and information relating to the order in which the service packets are communicated on a communications line between the source and destination nodes and (ii) comparing the communications data set against a pattern characterization data set to determine whether at least a portion of the plurality of service packets are part of the transaction. The pattern characterization data set includes information relating to a predetermined ordering of service packets that comprise the transaction. The method is amenable to non-intrusive/non-invasive measuring techniques and can provide near real-time response time information, even for multi-tiered computer networks.
The invention is based in part upon the recognition that the service packets communicated along the communications line constitute patterns of service requests that occur repeatedly in an operational environment. These service request patterns correspond to different transaction types. It has been discovered that these service request patterns can be determined using signal processing techniques. Once identified, the start and stop times for the pattern can be determined to provide a response time for the transaction.
A probe can be used to read the packets on a real-time basis from the communications line with the packets being recorded along with a received time (e.g., the time at which the packet was read by the probe) in the communications data set.
The packets can be filtered based on a node address and/or port number. In a preferred embodiment, the service packets correspond to a plurality of threads and the packets are sorted by thread.
The service request packets can be identified by their contents and destination. The service result packets can then be correlated with the corresponding service request packets. The start and stop times for the service request can then be determined.
After identification of the service requests corresponding to the transaction, the response time for the transaction can be determined using the various start and stop times for the service requests.
In another aspect of the present invention, a non-intrusive system is provided for identifying a transaction comprising a plurality of service packets communicated between source and destination nodes. The system includes: (i) a device for recording a plurality of service packets communicated on the communications line and (ii) a device, in communication with the recording device, for identifying a transaction that includes at least a portion of the plurality of packets.
In yet another aspect, the present invention provides a method for identifying a transaction comprising a plurality of service packets communicated between source and destination nodes that includes the steps: (i) providing a communications data set including (a) a plurality of service packets corresponding to a plurality of service requests and (b) the start and stop times for each service request and (ii) comparing the time interval between the stop of a first service request and the start of a second service request against a predetermined value for the time interval to identify a sequence of service requests that comprise a transaction.
The comparing step can be performed in several iterations where the time interval is varied to select an optimal predetermined value for the time interval between service requests to yield a substantially optimal listing of service request sequences as a possible transaction. The resultant number of transaction service request patterns are then used to determine an optimal value for the predetermined time interval. For a range of time intervals the number of transaction service request patterns remains constant. The optimal value for the predetermined time interval is the midpoint of this range of values. By way of example, after identifying a service request sequence(s) using the predetermined values, the method can further include selecting a second predetermined value, comparing the time intervals, between service requests, against the second predetermined value to identify a second sequence(s) of service requests corresponding to a second transaction(s), and recording the second sequence(s) of service requests and the number of occurrences of each of the second sequence(s) in a second data set. The method next selecting a third predetermined value (which is the optimal predetermined value) based on the relationship between (i) the number of the sequence(s) of service requests and the predetermined value and (ii) the number of the second sequence(s) of service requests and the second predetermined value. The method then comprises as before the time interval between service requests against the third predetermined value for the time interval to identify a third sequence(s) of service requests corresponding to a third transaction(s). The service request sequence for the third transaction is deemed to be the optimal sequence. The third sequence is then compared against the communications data set to determine whether at least a portion of the plurality of service requests correspond to one or more transaction(s).
The method produces the pattern characterization data set referred to above. The pattern characterization data set lists a plurality of service request sequences for comparison against the service requests from the comparing step. This additional comparison step is to determine if the service requests as ordered by time are contained in the pattern characterization data set.
In a final aspect, the present invention includes a non-intrusive system for determining transaction level activity between a source and destination node. The system includes: (i) a device for recording a plurality of service packets communicated on a communications line between source and destination nodes and (ii) a device for determining the number of transactions in communication with the recording device. The service packets relate to a number of transactions and the recording device provides the communications data set.
In one embodiment, the determining device is a device for comparing the time interval between the stop time of a first service request and the start time of a second service request against a predetermined value for the time interval to identify a sequence of service requests in the communications data set that together comprise a transaction.